30 Day Challenge Day 12 | Leetcode 256. Paint House

题解

动态规划，Easy级别。

动态规划题，重点是找到传递公式，思路见注释。

class Solution {
public:
    int minCost(vector<vector<int>>& costs) {
        if(costs.empty()) return 0;
        
        int n = costs.size(), m = costs[0].size();

        // dp[i][j]: The min cost with the current house painted color j 
        vector<vector<int>> dp(n, vector<int>(m));
        
        dp[0] = costs[0];
        
        // dp[i][j] = costs[i][j] + min(dp[i-1][not j])
        for(int i = 1; i < n; i++) {
            dp[i][0] = costs[i][0] + min(dp[i-1][1], dp[i-1][2]);
            dp[i][1] = costs[i][1] + min(dp[i-1][0], dp[i-1][2]);
            dp[i][2] = costs[i][2] + min(dp[i-1][0], dp[i-1][1]);
        }
        
        return *min_element(dp[n-1].begin(), dp[n-1].end());
    }
};